Archive for February, 2012
Getting a head of beer
With winter winding down my thoughts turn to warmer times ahead when the cover comes off the grill and a cold beer hits the spot. Last weekend my daughter and her husband motored down to New Ulm for Schell Brewery’s Bock Fest—a sure harbinger of Spring (and the desperation of home-bound Minnesotans). Increasingly I find myself turning to this next generation for keeping me on the bubble for brews. For example, I now know that it’s helpful to carmelize freshly-tapped bock beer by poking it with a red-hot iron—preferably one laid among fiery logs until glowing hot. 
But never mind that, I want to pass along some results from another of this younger set, Tracy Lenz, on a more mundane aspect of drinking beer—achieving just the right head of foam on the pour. For a graduate class in industrial engineering at Arizona State University (ASU) taught by DOE-guru Doug Montgomery, she used Design-Expert® software to experiment on foam height. A local microbrewer suggested that Tracy’s project team study keg pressure, temperature at keg and using Biofoam to make the brew more ‘sudsy’. The team included two very different beers in the same experiment design, which turned out to be problematic for modeling, so let’s concentrate on one—an American red ale.*
It turns out that red ales foam readily so they need no encouragement with Biofoam. Take a look at this response surface plot from the ASU study. Figuring on 2 centimeters of foam as a good head puts the sweet spot (shaded green) at the no biofoam (-1) side with pressure needed to be set low (-1). This result is achieved only if temperature is maintained at low level.
So there you go—a vital problem (especially for graduate-engineering students) solved. Just one catch though—how you pour the beer into the glass may be the biggest factor for achieving a good head. Here again the next generation comes to my rescue, for example last summer at an outdoor reception that featured a beer wagon with my favorite on tap: Lift Bridge Beer Company’s Farm Girl Saison ale. My glass foamed over no matter how I positioned it under the tap. It turns out that the trick is pouring along the side and then at just the right moment straightening up the glass while turning off the flow. See what I mean via this Youtube video. I found it easier just to stand by the beer wagon with an empty pint and a forlorn look until one of the younger fellows took pity on me. Cheers!
*I learned from one of my sons that an ale ferments at the top, whereas a lager ferments at that bottom. This is just one of many differences that are detailed by this beer-faq.
Obscurity does not equal profundity
Posted by mark in Basic stats & math, sports on February 12, 2012
“GOOD with numbers? Fascinated by data? The sound you hear is opportunity knocking.” This is how Steve Lohr of the New York Times leads off his article in today’s Sunday paper on The Age of Big Data. Certainly the abundance of data has created a big demand for people who can crunch numbers. However, I am not sure the end result will be nearly as profitable as employers may hope.
“Many bits of straw look like needles.”
– Trevor Hastie, Professor of Statistics, Stanford University, co-author of The Elements of Statistical Learning (2nd edition).
I take issue with extremely tortuous paths to complicated models based on happenstance data. This can be every bit as bad as oversimplifications such as relying on linear trend lines (re Why you should be very leery of forecasts). As I once heard DOE guru George Box say (in regard to overly complex Taguchi methodologies): Obscurity does not equal profundity.
For example, Lohr touts the replacement of earned run average (ERA) with the “Siera”—Skill-Interactive Earned Run Average. Get all the deadly details here from the inventors of this new pitching performance metric. In my opinion, baseball itself is already complicated enough (try explaining it to someone who only follows soccer) without going to such statistical extremes for assessing players.
The movie “Moneyball” being up for Academy Awards is stoking the fever for “big data.” I am afraid that in the end the call may be for “money back” after all is said and done.